Papua New Guinea

Resources

Geography

Geographic description

Papua New Guinea lies in the southwestern part of the Pacific Ocean and covers a land area of 462 840 km2 between latitudes 0° and 12° S and longitudes 141° and 156° E. The country consists of the eastern half of the island of New Guinea, the Trobriand, Woodlark, d' Entrecasteaux and Louisiade groups of islands, the Bismarck Archipelago with New Britain, New Ireland and Manus and the Buka and Bougainville islands of the Solomons.

The central core of New Guinea is a massive mountain chain with peaks up to 4 500 m (Mount Wilhelm 4 508 m), forming a natural east-west barrier. The mountain chain is made of a series of ranges divided by large fertile valleys at altitudes between 1 500 and 1 800 m. High rainfall is responsible for the many rivers, but most are navigable only in their lower parts. Exceptions are the Sepik River in the north and the Fly River in the southwest, both with extensive herbaceous grass swamps. Southwestern New Guinea is a flat land covered with dry evergreen forests.

The island regions also have prominent mountains but of much lower elevation. The highest peaks on New Britain are up to 2 438 m, on Bougainville up to 2 743 m and on New Ireland up to 1 871 m. These islands, with recently latent but still active volcanoes, have highly fertile soils where most of the agricultural activity and production of the country is concentrated.

The climate is moist and tropical except in the southwestern and central southern areas. The southwestern monsoon, which is hot and humid and brings most of the rain, occurs from December to May. High mountains and the insular nature of part of the country have a strong effect on the local climate. The central mountain chain is a rain shelter for the southwestern part during the northwest monsoon and so this part is much drier and covered with savannas. There is considerable variation in annual rainfall, ranging from 980 mm at Port Moresby to more than 5 000 mm in places in the central mountains, where rainfall occurs all year. Temperatures average about 30° C along the coast in the north and show a marked seasonal tendency southward. In the highlands, temperatures range between 9° and 32° C (with frost at higher elevations) and between 23° and 32° C at Port Moresby.

Forest cover

Description of the natural woody vegetation

Papua New Guinea has a variety of forest types ranging from savannah woodlands, swamps and mangroves to lowland rainforests, hill forests and montane forests. Extensive areas of grasslands are found in the highlands and in the south-west. The description of the vegetation types is based on White (1971), Havel (1972), Minister of Forests (1973), Paijmans (1975) and Whitmore (1975).

Natural forests

Closed broadleaved forests

Lowland rainforest (up to 1 500 m)

Unlike the forests of southeast Asia, dipterocarps are not the dominant family in the canopy of the evergreen rainforest. They are replaced by a number of other species among which Pometia pinnata (especially on the plains), Ficus spp., Alstonia scholaris and Terminalia spp. are constantly present in the upper storey. Locally predominant, according to drainage and soil, are kwilia (Intsia spp.), New Guinea rosewood (Pterocarpus indicus) and the dipterocarp Anisoptera thurifera (or A. polyandra) that, together with Hopea spp., forms a common association on ridges and foothills.

On well-drained sites with deep soils the canopy is well over 30 m and emergents may extend over 50 m. Undergrowth usually consists of vines, many palms, scrub and rattans. On poorly drained soils an open forest occurs with Planchonia papuana, Bischofia javanica, Terminalia complanata, Cananga odorata, Intsia spp. and others.

An interesting feature of the composition of the lowland forests is the large component of species of secondary succession types. These fast-growing light-demanding species reach large sizes and are the most valuable wood species in the forest. Their presence is dependent on natural disturbance phenomena such as landslides or intervention by man. The most important species of this group are Pometia spp., Anisoptera thurifera, Alstonia scholaris, Spondias dulcis, Terminalia spp., Octomeles sumatrana and others. These forests can be divided into fairly homogeneous systems:

• The "west Papuan forest system", where the Fly river emerges from the mountains, is a belt of rainforest in which dipterocarps like Anisoptera, Hopea and Vatica spp. are mixed with many non-dipterocarp species, principally of the genera Canarium, Eugenia and Lithocarpus. On steep slopes Vatica rassak is the most common tree species in all layers. Low- lying areas are frequently flooded during periods of high rainfall;

• The "Papuan south coast forest system" has Pometia spp. as the dominant species. Its composition varies greatly according to the relief. On hilly terrain Hopea and Anisoptera spp. are more abundant;

• The "south-east coastal forest system" extends along the generally narrow coastal plain and foothill area. The forests are dominated by Anisoptera thurifera, especially in the foothills where they form nearly pure stands. They extend virtually into permanent swamp areas. Other important species are Pometia spp., Hopea spp., Pterocarpus indicus, Planchonella spp. and others;

• The "Solomon forest system", has a composition similar to that of the Bismarck system but with local concentrations of Vitex cofassus;

• The "Sepik-Ramu forest system" is formed by lowland rain forests dominated by kwila (Intsia spp.) with local concentrations of Agathis labillardierei, especially in the Torricelli mountains and south of the Sepik river. Other species are the usual lowland species such as Pometia spp., Terminalia spp., Palaquium spp., Eugenia spp.and Planchonella spp.

With increasing altitude the forest canopy becomes less variable in height (25 to 30 m), closure (60 to 80 %) and crown size. Emergents, with the exception of Araucaria, are lower, reaching 40 m. Trees with large diameters and buttresses become less common but the total number of trees above 30 cm is greater. This forest is very mixed floristically.

Locally, a small-crowned hill forest occurs corresponding to particular soil conditions. In this type, frequent species are Castanopsis acuminatissima, Hopea papuana and the drought-tolerant Casuarina papuana.

Lower montane and montane forest

This type of forest is generally found above 900 to 1 000 m and extends up to 3 500 m. The canopy height decreases to 15 to 25 m and emergent trees are often absent except for Araucaria spp. Undergrowth is abundant. Oaks (Castanopsis acuminatissima) and laurels (Cryptocarya) are prevalent. Upward, generally above 2 000 m, beech forest prevails, with the valuable southern beech (Nothofagus spp.) in mixed stands occupying the ridges. In the upper zone, above 3 000 m, an Ericaceae forest develops with Papuacedrus spp. locally present. The canopy is only 12 to 18 m high. At higher elevations the height of the canopy gradually decreases and on Mount Wilhelm, between 3 500 and 3 900 m, subalpine scrub forest is only 4 to 5 m high.

Mangrove forest

Mangrove forests fringe large parts of the coast and form very extensive stands along the Gulf of Papua, near Lae and Madang and in the Sepik estuary. They also occur elsewhere in smaller stands. Most of the mangrove area is very sparsely populated and almost virgin. The general zonation of the mangrove communities appears to be similar to that of south-east Asia and is dominated by Rhizophoraceae. In the Papuan Gulf, Rhizophora spp. and Bruguiera spp. are most common and frequently attain large dimensions.

Fresh water swamp forest

Fresh water swamp forests occur in south-western New Guinea along the Fly River, in northern New Guinea along the Sepik River and also behind mangroves and along several river courses in the intermontane basins. These swamps are regularly inundated by mineral rich fresh water. One tree species often dominates the canopy, which is 20 to 30 m high with emergents reaching 40 m.

Throughout New Guinea Campnosperma brevipetiolatum is common and occurs in pure or nearly pure stands. The sago palm (Metroxylon sagu) also forms large stands, sometimes in combination with the former species. Other frequent swamp species are Campnosperma auriculatum, Nauclea coadunata, Syzygium spp., Alstonia spp., Terminalia spp., Dillenia papuana and Planchonia timorensis.

Large areas of southern Bougainville, in the regions of Tonolai, the Luluai River and Empress Augusta Bay, have extensive swamps with almost pure stands of Terminalia brassii in association with Campnosperma brevipetoliatum forests.

In the northern part of Papua New Guinea, pure stands of 50 m tall Casuarina cunninghamiana occur as pioneer vegetation on swampy alluvial soils.

Throughout New Guinea Melaleuca spp. that are understorey species in the primary swamp forest become dominant after disturbance.

Littoral forests

These forests are confined to coastal sandy beach plains and are characterised by a canopy of medium height and an abundance of palms in the shrub and lower tree layers. Common trees are Pterocarpus indicus, Terminalia spp., Planchonia papuana, Nauclea coadunata, Pongamia pinnata, Syzygium spp., Melaleuca, Casuarina equisetifolia, and, in the south-west, Acacia.

Deciduous forests

A belt of slightly deciduous forest is present inland from the south-central coast as a transition between savannah and the evergreen forests. This belt is probably due to a combination of seasonal drought stress and shallow soils. Frequent deciduous trees are Garuga floribunda, Brachychiton carruthersii, Intsia bijuga, Terminalia spp., Protium macgregorii and Sterculia spp.

Forests with a marked deciduous character exist in the coastal limestone hills near Port Moresby where the annual rainfall is less than 1 200 mm. Other species, in addition to those above, are Gyrocarpus americanus, Bombax ceiba, Albizia spp., Maniltoa spp., Adenanthera pavonina and Erythrina spp. This forest has a low and open canopy and in places grades into woodlands.

Dry evergreen forests

These are restricted to relatively low rainfall areas in the south-west on imperfectly drained and gently undulating land. The most common trees are mainly non-deciduous and the tree stratum is relatively open. Epiphytes are poorly developed. Frequent tree genera are Acacia, Tristania, Syzygium, Rhodamnia, Xanthostemon, Maranthes, Mangifera, Rutaceae, such as Halfordia and Flindersia, and Proteaceae such as Oreocallis and Grevillea. Near the Indonesian border dry evergreen forest locally grades into woodland with a dense understorey of tall bamboo. Frequent fires lead to the replacement of dry evergreen forest by woodland and ultimately savanna with fire-tolerant species.

Coniferous forests

Conifers are widespread in the forests of Papua New Guinea but in most cases they do not constitute the dominant part of the forests. However Araucaria spp. in the upper lowland and montane forests and a community of several conifers in the upper montane forests sometimes form pure stands or are dominant.

Two species of Araucaria occur in the upper lowland and montane forests of Papua New Guinea, the klinki pine (Araucaria hunsteinii) and the hoop pine (Araucaria cunninghamii). The hoop pine is present between 90 m and 2 800 m elevations and the klinki pine occurs between 500 and 2 100 m, mainly in the valleys and on the slopes of the central cordillera. Both species are most abundant in the Wau and Watut valleys of the Bulolo river. Here, in the rainshadow of the inland valley, klinki forms dense stands on the valley floor in the discontinuous emergent stratum of the semi-evergreen forests. In the montane forest, hoop pine replaces klinki with increasing elevation. Elsewhere, both occur in a very wide ecological range but generally in smaller groups. The trees can form giant columns of one metre in diameter and 60 to 75 m in height.

In the New Guinean montane forests, conifers are frequent. Podocarpus is common in the lower montane forests and, above 2 400 m, belts of some width with trees up to 36 m tall occur, mainly composed of Dacrydium novoguineense, Papuacedrus spp., Phyllocladus hypophyllus and Podocarpus spp. Patches of either Myrtaceae or Dacrydium elatum and Podocarpus papuanus are found in the boggy depressions.

Bamboos/palms

Bamboo scrub with emergent tree ferns is extensive on steep, ash-covered slopes in central and northern Bougainville mainly between 600 and 1 200 m. The type appears to be rather stable and may form an arrested successional stage.

Open broadleaved forests

Woodlands

Dry woodland commonly replaces marginal forest after the forest's delicate balance has been disturbed by fire, but also occurs naturally on sites where adverse conditions of climate and soil have prevented the development of forest. It is found on a variety of landforms, mainly in the monsoonal areas of the south-central coast and south-west Papua New Guinea.

Woodland has a low, open canopy, but the shrub layer is usually dense and thin woody climbers often abound. Grasses, ferns and sedges form a sparse ground cover. The most frequent trees are those of the forest it replaces or grades into; i.e., small-crowned lowland hill forest, dry evergreen forest or littoral forest.

Woodland that is subject to periodic flooding occurs on poorly drained flats, mainly in south-west Papua New Guinea, and throughout the country forms narrow bands around permanent swamps, lakes and lagoons that have a fluctuating water-table. Common trees are Carallia brachiata, Nauclea coadunata and, in south-west Papua New Guinea, species of Melaleuca, Acacia and Tristania.

Gallery woodland lines small streams within savanna and grassland. Many of its canopy trees are deciduous and bamboo is a common feature in the undergrowth. It is probably the remnant of more extensive forest or woodland cover.

Woodland on beach ridges occupies a zone between pioneering herbaceous vegetation and scrub to seaward and forest to landward. It characteristically contains pantropic trees such as Calophyllum inophyllum, Barringtonia asiatica, Terminalia catappa and Pandanus tectorius.

Swamp woodland occurs in permanent and near-permanent shallow swamp. It is extensive in swamps associated with the lower courses of large rivers such as the Mambare, Lakekamu and Purari rivers. Except for a more open tree canopy it is similar in structure to swamp forest, and many of the same trees are common to both types. On sites that have a strongly fluctuating water level many trees develop adventitious roots. Carallia brachiata and Syzygium spp. are common. Near the coast, trees characteristic of brackish swamp predominate and the fern Acrostichum appears in the ground layer. Where the environment is brackish as well as monsoonal, trees such as Excoecaria agallocha and Melaleuca spp. are common.

Savanna

Three different types of savanna can be distinguished:

• Eucalypt savanna is the most common type, occurring from sea level to about 1 700 m on a variety of land forms that are never flooded. In hilly terrain, eucalypt savanna is commonly confined to crests and upper slopes while the lower slopes and valley bottoms remain in forest. In areas with an annual rainfall of less than about 1 300 mm and a severe dry season, with up to seven months totalling less than 100 mm, eucalypt savanna completely covers hills, undulating terrain and plains. Eucalypt savanna is most extensive along the south-central coast, but is also present in intermontane valleys in the central range some 150 km east of Port Moresby. In these valleys it probably reaches the central north coast near Popondetta. Eucalypt savanna consists of a tree layer of one or more of the species Eucalyptus alba, Eucalyptus confertiflora, Eucalyptus papuana and Eucalyptus tereticornis, and a ground layer of mid-height grasses, the most frequent of which are Themeda australis and Imperata cylindrica. Eucalyptus tereticornis is present over the whole elevation range of eucalypt savanna and tends to dominate on sites having deep soils. It usually has a straight bole and grows to a height of over 30 m. The other savanna eucalypts are only present at lower elevations. They usually have crooked stems and do not normally grow over 20 m high;

• Melaleuca savanna is the next most common type of savanna. Occurring from sea level to 500 m, Melaleucasavanna is characteristic of seasonally inundated or waterlogged plains and fluctuating riverbank swamps although it also grows on permanently dry hilly terrain. It is mainly found in regions with a relatively low and seasonal rainfall in freshwater environments, on brackish sites behind mangroves and on slightly alkaline soils of beach plains. Although most extensive in south-west Papua New Guinea, it also occurs along the south-central coast and, rarely, on the north side of the central ranges. Melaleuca savanna is also found on hilly terrain on the d' Entrecasteaux islands, which have a fairly evenly spread rainfall in places as high as 2 500 mm or more. Various species of Melaleuca are present, all of which tolerate burning, prolonged inundation and periodic drought. Most frequent are Melaleuca cajuputi, Melaleuca leucadendron and, particularly in south-west Papua New Guinea, Melaleuca viridiflora. Individual stands consistpredominantly of a single species;

• Mixed savanna is restricted to south-west Papua New Guinea and occurs on undulating to flat terrain varying from permanently dry to seasonally waterlogged or inundated. Its structure and floristic characteristics vary with the depth and duration of inundation and the frequency of burning. On well to imperfectly drained terrain, mixed savanna is 20 to over 30 m high and relatively dense. Shrubs are also tall and dense and compete with the grasses Imperata cylindrica, Ophiuros tongcalingii and Ischaemum barbatum in the ground layer. The most commonof the many genera of trees present are Tristania, Melaleuca, Acacia and Xanthostemon. Eucalypts, except Eucalyptus alba but including Eucalyptus polycarpa, are present in many places but are nowhere dominant.

Other wooded land

Shrubs

Scrub occurs on sites that are unsuited to the growth of forest and woodland because of harsh climatic conditions and/or soil deficiencies. In lowland regions that have a strongly monsoonal climate, scrub occurs on coastal limestone hills, beach ridges, and periodically inundated, often alkaline, plains. In high mountain regions it occurs above the tree line and on steep summit ridges that have shallow stony soils.

Scrub consists of dense shrubs up to about 6 m high. Scattered low trees are usually present. In coastal monsoonal scrub, Hibiscus tiliaceus, Desmodium umbellatum and, on temporarily inundated terrain, Pluchea indica are common and Flagellaria indica is a common climber.

Sinoga lysicephala scrub, in mosaic with low sedge-grassland, covers large areas of seasonally inundated plain in southwest Papua New Guinea.

In high mountainous areas scrub consists of true shrubs such as Coprosma divergens, Epacridaceae and Ericaceae and trees that are reduced to a shrub form such as Pittosporum pullifolium, Xanthomyrtus and Papuacedrus papuanus.

Absent the forest inventory report, the figures in this report appear to be the best available in this office. Hopefully, better information is available from the country. This publication quotes figures from “Forest Resources and Vegetation Mapping of Papua New Guinea PNGRIS”, not available in this office.

Information content (check one or more topics as appropriate)

Natural Forest

X

Protected areas

Plantations

Biodiversity

Other wooded land

X

Forest ownership

Forest area change

Wood supply potential

Total volume

Non-wood forest products

Total biomass

Trees outside forest

Commercial volume

Forest fires

Name of reviewer: Jim Space

Table 2 - Description of forest inventories/surveys

Country

Papua New Guinea

Reference year

1993?

Title of inventory

Forest Resources and Vegetation Mapping of Papua New Guinea PNGRIS as quoted in the Draft National Forest Plan (Sixth Revised)

Type of inventory

Not known

Field / aerial photos / satellite images / ...

Brief summary of methodologies used

Not known

Reporting level

National

Country coverage

Complete

National / sub-national

Complete / partial

Map output

Yes

Scale of the map

Not available

yes / no (also indicate format: analogue / digital)

Vegetation types included

yes/no

Additional information included

yes/no

Natural forests

X

Area by forest formation

Plantations

Volume

All forests

X

Biomass

Other wooded land

Forest naturalness

Forest biodiversity

Forest ownership

Wood supply potential

Remarks

This is second-hand information. Original report not available in the FAO library.

Reliability class

?

1=high 2=medium 3=low

Table 3 - Area of woody vegetation according to national classification

Reference year: 1993? Geographic Unit: Papua New Guinea

Forest and other woody vegetation types

(country classification)

Area

(000 ha)

1.Closed forest – Production forest, acquired operable

3724.33

2. Closed forest – Production forest, acquired inoperable

5028.70

3. Closed forest – Future production forest

3219.47

4. Closed forest – Reserve potential forest

8225.90

5. Closed forest – Reserve montane and inundated forest

17451.75

6. Closed forest – Protection forests

1665.70

7. Forest fallow? – Other areas*

Subtotal of country classes corresponding with FRA 2000 forest and other wooded land

39315.85

Subtotal other land

6968.15**

Total land area

46284***

Definitions: *Not otherwise defined

Comments: **Obtained by subtraction. Given as 6709.36 in the cited publication.

NFS (1998) presents plantation area as 57 957 ha in December 1997, with breakdown by ownership and main species. Anon. (1996) gives annual planting target as 4 000 ha. Supposing this is valid up to the year 2000, applying this to the total of the year 1997 as a base, the total of the year 2000 is estimated to be approximately 70 000 ha. Ownership is assumed to be the same as in 1997, 39 percent of the whole plantation is owned by the state.

Only indicative information on species breakdown is available. Pandey (1997) estimates species composition, there is no data later than this, thus this applied for the data of the year 2000.

Regarding the purposes, Anon (1996) says that coniferous plantations are supposed to produce timber. Thus they are categorised as industrial plantations. There is no information about purposes of broadleaved species.

Apart from other species, IRSG (1997 and 1999) give rubber plantation areas in 1988 and in 1996. Using these figures, annual planting rate and the total plantation area are estimated as 400 ha and 19 800 ha, respectively. This should be included in plantation.

Regarding non-forest species, coconut and oil palm plantations are established. APCC (1998) and ISA (1999) give their area by several years, total areas of the year 2000 are estimated.

References

Anon. 1996. Country Statement: Report to the 16th session of the Asia-Pacific Forestry Commission, Yangon, Myanmar, January 1996.